Managing Spongy Moth (LDD moth)

The Spongy Moth (also known as Lymantria Dispar Dispar or LDD moth), formerly known as the European Gypsy Moth, is a defoliating (feeding on leaves) insect that is considered a major pest in North America. The caterpillar, or larva stage of the insect, eats the leaves of trees making them more susceptible to disease and damage from other insects.

Spongy Moths have been present in Brampton for more than 10 years. Over the last three years, in Brampton and neighbouring municipalities, populations of Spongy Moth have reached higher than normal levels.

To control the population growth and protect vulnerable trees from defoliation, the City of Brampton is taking on additional measures as part of an Integrated Pest Management program.

Frequently Asked Questions

Will the City be conducting an aerial spray in 2023?

No, the City will not be conducting an aerial spray this year. Aerial sprays are conducted in response to large scale, widespread increases in Spongy Moth populations, when Spongy Moth numbers pose a high risk to the tree canopy, and no other control measures are able to keep populations within manageable thresholds. As such, an aerial spray will not be necessary for 2023. City management will focus on ground base spraying of trees along particular streets and in parks. Ground base spraying is the use of a hand held applicator which target individual trees. All trees will be inspected by a specialist and they will determined if spraying is required. Once spraying is deemed necessary, the affected residents will be notified.

What is a pheromone trap?

Pheromone traps are an important tool in Spongy Moth management. Pheromone traps are made of green cardboard and shaped like small milk cartons. They are usually attached to trees during the summer. Inside each trap is a small paper strip coated with the Spongy Moth pheromone - the bait for the trap. The pheromone is the chemical "perfume" that female Spongy Moths give off to attract male moths. The males fly into the traps and are caught. Pheromone traps will be collected later in the summer or fall, and the number of Spongy Moths in each trap is counted.

What should I do if I find a pheromone trap near my property?

Please don't disturb the trap. The pheromone trap will be removed in late summer by City staff. The number of moths caught in each trap will help City staff locate or track Spongy Moth populations. The quality of the trapping data is reduced whenever a trap is lost or damaged.

Will pheromone traps attract Spongy Moths and cause a new infestation to start?

No, because only male Spongy Moths are attracted to the pheromone traps. Female Spongy Moths cannot fly and are not interested in the pheromone. Infestations can only occur when female Spongy Moths are present and lay eggs.

How is Btk applied?

The City of Brampton will be using hydraulic sprayers, as ground level spraying is a viable treatment option for the eradication of Spongy Moth when populations are small and isolated in known areas. Ground spraying can specifically target potential host vegetation without impacting other objects like houses, fences and non-host trees and shrubs.

How does Btk work?

Btk is a naturally occurring bacteria found in soil. It must be eaten by the larvae (caterpillar) of the Spongy Moth and once ingested, produces a protein that is only harmful to the susceptible insect. This protein stops the caterpillar from eating and the insect dies within two to five days. For Btk to be activated, the alkaline conditions that exist only in certain insects' digestive systems must be present.

Are pheromone traps harmful?

The pheromone is not toxic to humans, other mammals, birds, fish or insects. The traps will only attract adult male Spongy Moths. The pheromone traps do not have insecticide in them but instead have a cardboard strip coated with a sticky material to trap the moths.

What does the damage look like?

Spongy Moth caterpillars chew small holes in the new leaves. As the caterpillars begin to grow, they eat more and the holes become larger until only the leaf veins remain. When population levels are high, Spongy Moth caterpillars have the ability to strip trees of all of their leaves.

How do I protect myself and my family from Btk?

The following measures may be considered by residents living in the treatment area:

Whenever possible, remain indoors for 30 minutes after spraying to allow the droplets to deposit onto the tree leaves.
Bring laundry, toys and pets indoors before spraying begins.
Cover lawn furniture, outdoor tables, pools, BBQs, play equipment and sandboxes and/or rinsing them off with water after spraying is finished.
Minimize opening and closing windows and doors during the spraying.
Contact your family physician if you are concerned that a personal medical condition may be aggravated by the spraying.

To learn more, visit https://www.canada.ca/en/health-canada/services/pest-control-tips/gypsy-moths.html

What kinds of trees are most affected by the Spongy Moth caterpillar?

Spongy Moths prefer oak trees but will eat all kinds of hardwoods including elm, birch, poplar and willow trees. In some rare cases, when the number of Spongy Moths is extremely high, the caterpillar will feed on evergreens such as pine and spruce. They do not appear to like sycamore, butternut, black walnut, dogwood or balsam fir.

What does the European Spongy Moth look like?

Spongy Moth caterpillars change as they grow. Young caterpillars are black or brown and about .5mm (.24 inches) in length. As they grow, bumps develop along their backs with coarse black hair. The caterpillar is easily recognizable in the later part of this stage: charcoal grey with a double row of five blue and six red dots on its back. Feeding ends by early July, and mature caterpillars can be as long as 60mm (2.5 inches). Adult male moths are greyish brown and can fly and survive about one week, mating with several different females. Females are larger and whitish with darker zigzag marks. The female cannot fly and dies shortly after laying her eggs.

What is the life cycle of the Spongy Moth?

The moths are seen only in mid-summer. They exist only to mate and after the female lays her eggs, moths of both sexes die. They lay their egg masses on the limbs and trunks of trees, on rocks, buildings, vehicles or in other sheltered areas. The masses remain in place all winter and will hatch the following spring from late April to mid-May.

Is Btk safe?

Btk has been approved by the Pest Management Regulatory Agency (Health Canada) for use in urban areas. It has been applied in the Greater Toronto Areas over a number of years. Btk is one of the few pesticides acceptable to organic growers.

The public is unlikely to experience any symptoms and no special precautions are necessary or required. Btk spraying is not expected to have adverse effects on vulnerable populations including children with asthma, people with weakened immune systems, pregnant women or the elderly. Individuals who have concerns should take reasonable precautions to avoid exposure during a spray program.

To learn more, visit https://www.canada.ca/en/health-canada/services/pest-control-tips/gypsy-moths.html

2023 Spongy Moth Management Plan

During the winter months, Horticulture and Forestry staff conducted egg mass scrapping in some parks and streets. The removal of the egg masses help lessen the numbers of larva hatched in the coming season and reduce damage to trees.
In June, staff will be spraying street trees and woodlot edges with btk to control the caterpillars. These areas have been identified from egg mass counts conducted over the winter months. Btk has been approved by the Pest Management Regulatory Agency (Health Canada). Staff will only spray trees that are located on City property they will not spray trees on private property. Notice to residents in these areas will be provided in advance of spraying.
This July, Parks staff will be installing pheromone traps in selected woodlots to detect the numbers for future egg mass counting. Staff will be monitoring the traps and removing them in August.